The FAA have just issued an advisory circular with regard to the provision of NOTAM via the Internet, you can find it at
http://www.aopa.org/whatsnew/newsitems/2002/ac00-62.pdf
It includes, with reference to becoming a Qualified Internet Communications Provider (QICP) the following requirement:-
2. GENERAL. A person or organization that accomplishes and maintains the following as they pertain to the provider's facility (i.e., all hardware, software and Internet connectivity under the applicant’s direct control) may become an approved QICP:
a. Reliability means users are able to retrieve requested data from the provider with no outage lasting longer than 10 minutes, and no more than 30 minutes of total outages (including outages due to maintenance) in any continuous 3-month period.
b. Accessibility means turnaround time within the provider's facility. The provider should be capable of initiating transmission of requested data during transactions with 100% of its users within 2 minutes.
Nearly three months down the line Thales IS and NATS are nowhere near achieving this standard.
Mike